1. Technical Field
This invention relates to cows, more specifically to a method and apparatus for detecting heat and managing breeding in cows.
2. Background
Commercial raising of cattle for either beef or dairy production requires proper management. In addition to the various husbandry concerns such as herd health and nutrition, a critical management area for economic survival of any cattle operation, is the breeding management of the cows, in the case of beef cows without successful breeding, there are no calves produced and therefore no product to sell. In the case of dairy cows, the cows will not produced milk unless they have a calf, which is again dependent upon successful breeding management.
While breeding management is important in any cattle operation, the timing of breeding and breeding intervals are generally more critical in dairy operations. Dairy cows are managed more intensely and often bred exclusively by artificial insemination. In natural matings, a bull will service a cow numerous times during each fertile receptive cycle. With artificial insemination, the object is to inseminate the cow the minimum number of times possible to insure pregnancy during that fertile cycle. There are costs associated with both each unit of semen used on the cow, as well as increased labor costs with increased numbers of matings; this is why it is important to both minimize the number of inseminations and yet still have a high probability of the cow becoming pregnant.
A basic understanding of fertility and the estrous cycle of the cow is necessary for appreciation of existing management problems and solutions. The estrous period in cattle occurs approximately every 21 days in non-pregnant or open cows. The cow then remains in estrus for approximately 12-24 hours. The cow ovulates approximately 14 hours after estrus. The time of ovulation is the optimum time for artificial insemination. If the cow is successfully inseminated, she will become pregnant for approximately 280 days. Dairy cows are managed such that they are ideally bred and become pregnant again 45 to 60 days after calving. The dairy cows are preferably maintained pregnant to insure milk production.
If the desired estrous cycle, for example, the first post-partum estrous cycle, is not detected or if the cow is not successfully bred during a particular cycle, the cow cannot be bred for at least another 21 days. It is estimated that for every day past a set goal date that a cow remains open, there is an economic loss of between $1.00-$3.00 per day. An average sized dairy herd is between 200 to 1,000 cows. If the 24 hours during which the cow should be bred is missed for each cow, this represents an economic loss of $4,200.00 to $21,000.00 annually. Often cows are not successfully bred for as many as 3 estrous cycles, due to infertility, infections and semen-related problems. If one half of the cows in a herd of 200 to 1,000 is not impregnated for 3 cycles, the estimated economic loss increases to $6,300.00 to $31,500.00 annually. These projections of economic loss to the producer demonstrate the critical importance of determination of the onset of estrus in cattle management.
A number of management techniques are used to detect estrus in cows. These techniques include rectal palpation of the cow's reproductive tract, tracking changes in the viscosity of the vaginal mucous discharge from the cow, and observing behavioral changes associated with estrus in cows.
Observing the behavioral changes of a cow in estrus is one of the most widely used management techniques and is used either alone or in conjunction with other techniques. During the fertile portion of a cow's estrous cycle, a cow will attempt to mount other cows and stand in place and allow other cows to mount and ride her. Likewise, when a cow is in estrus, other cows are stimulated to mount and ride her. Because of the short 12-24 hour duration of the time for breeding the cow, the cows must be observed at least twice a day in order to avoid having a fertile cycle go undetected. Most dairy cows are milked twice daily at 12-hour intervals. Many producers use this time of gathering the cows for the milking parlor to look for signs of cow-cow jumping and standing for mounting that are indicative of a cow in estrus. Observing the cows when they are gathered at milking time increases the likelihood of identifying the cows that are in good behavioral estrus. However, if the cows are uncomfortable or distracted at these times, for example, if the weather is too hot, cold or wet, or there is loud equipment operating nearby, the cows will not show signs of behavioral estrus at these easily observable milking times. Often the cows will wait until the cool part of the night to increase their activity levels, including mounting behaviors.
To aid in this detection of behavioral estrous, a number of aids have been developed. Rule et al., U.S. Pat. No. 3,026,431, and Larson, U.S. Pat. No. 3,158,134, both describe devices that are glued to the rump of a cow and show a change in appearance in response to the pressure applied to the devices by a mounting cow. Magrath, U.S. Pat. No. 4,696,258, shows a microencapsulated paint that is similarly applied to the cow's rump and changes appearance in response to the pressure of amounting cow. These devices have been found to have an incompatible shelf life with the management systems that utilize them. A similar device with a longer shelf life is Griffin et al., U.S. Pat. No. 4,239,018.
A problem with all of these devices is that they often are difficult to see. In many regions of the country during the winter, there are only 6-8 hours of day length. With short days lengths, one or both of the easily observable times for estrous detection at milking will be in the dark. Another factor that makes these devices difficult to see is that the color of the cow's body is sometimes in low contrast to the detection device.
A number of other devices exist that utilize electronic monitoring systems, such as Leonardo, U.S. Pat. No. 4,635,587, Senger et al., U.S. Pat. No. 5,111,799, and Bielka, U.S. Pat. No. 4,206,766. All of these electronic systems are generally not cost effective and have an increased likelihood of failure due to the increased number of parts and complexity.
Another problem with all of these systems is their inability to tell you the reproductive status of the cow other than that she has been mounted. In Wassileiff et al., U.S. Pat. No. 3,942,475 the use of a sleeve for removable replacement of differently colored indicators for facilitating color coding is disclosed. However, Wassileiff does not indicate a reason or method for use of the color coding.
To improve the breeding management of cows and decrease the economic losses associated with the nonpregnant interval it is important for the producer to be able to tell as much as possible about the cow when she is observed.
Other information, other than merely that the cow has been mounted, that is important for managing the cow includes whether or not the cow has been bred, whether or not the cow has been treated for infection or infertility and what should be done with the cow during the present estrous cycle. There are a number of management decisions to be made regarding a cow showing estrus such as whether she should be checked or treated for infertility because she has already been artificially inseminated and has had another cycle, the length of the particular cycle as an indication of cystic ovaries or early term abortion, and whether she should be treated therapeutically, culled or inseminated again and with what quality of semen.
What is still needed is a pressure responsive apparatus for detecting estrus in animals that exhibit estrous-related mounting behavior that can be more easily visualized and can also be seen in the dark.
What is also still needed is a method for managing the reproductive status of cows comprising using a plurality of different color pressure responsive estrous detection devices wherein each color, of device indicates a particular breeding management status for the cow.